1. Field of the Invention
The present invention relates generally to immunology and adenoviral gene therapy. More specifically, the present invention relates to immunomodulation by genetic modification of dendritic cells and B-cells and applications of CD40-targeted adenoviral vectors in vaccination against tumor cells.
2. Description of the Related Art
An expanding body of evidence suggests that dendritic cells (DC) play a pivotal role in the immune system [Bancheareau and Steinman, 1998, Nature. 392:245]. Foremost, dendritic cells are recognized to serve as a key mediator of T cell based immunity. Stemming from their important function, dendritic cells have been proposed for utility in a number of clinical strategies, especially vaccinations. It has become clear that genetic modification of these cells can promote immunity against pathogenic entities, both infectious and tumorigenic [Reeves et al., 1996, Cancer Res. 56:5672]. Importantly, all of these strategies are predicated upon efficient vectors for gene delivery to dendritic cells. To this end, a number of approaches have been utilized, albeit generally with poor efficiency of gene transfer [Arthur et al., 1997, Cancer Gene Ther. 4:17; Van Tendeloo et al., 1998, Gene Ther. 5:700]. One candidate vector for gene delivery has been replication defective adenoviral vector. This vector has been suggested to be well suited for clinical applications by virtue of its high titer, efficiency gene delivery and exuberant gene expression.
In spite of these theoretical advantages, the relative resistance of dendritic cells to adenoviral vector infection has confounded obtaining the full benefit of gene based immunotherapy strategies. [Arthur et al., 1997, Cancer Gene Ther. 4:17; Dietz and Vuk-Pavlovic, 1998, Blood. 91:392]. The phenomenon of dendritic cell resistance to adenoviral mediated gene transfer may be based upon the paucity of adenoviral entry receptors. In permissive cells, the projecting adenoviral fiber-knob protein mediates binding to the cell surface coxsackie-adenovirus receptor (CAR) followed by interaction with and internalization of the virion by either of the αv integrins αvβ3 or αvβ5 [Bergelson et al., 1997, Science, 275:1320]. High efficiency gene transfer independent of CAR expression by means of adenovirus targeted by bispecific entities to alternate cellular receptors has been shown [Douglas et al., 1996, Nature Biotech. 14:1574].
As a result of advances in the identification of tumor specific and tumor associated antigens, antigen directed immunotherapy is emerging as a rational approach for the treatment of cancer. To this end, dendritic cells are regarded as the predominant antigen presenting cell of the immune system; the role of “mature” dendritic cells in the activation of T cells is particularly relevant to immune responses against tumors [Banchereau et al., 1998, Nature 392:245; Mayordomo et al., 1997, Stem Cells 15:94]. In many instances antigen presentation by dendritic cells is regarded as a rate limiting step in the generation of anti-tumoral immunity [Mayordomo et al., 1997, Stem Cells 15:94; Celluzzi et al., 1998, J. Immunol. 160:3081]. For these reasons, dendritic cells represent a unique junction for intervention by antigen-specific vaccination strategies.
In this regard, strategies that employ antigen pulsed dendritic cells have proven remarkably effective at protecting animal models from tumor challenge [Mayordomo et al., 1997, Stem Cells 15:94, Reeves et al., 1996, Cancer Res. 56:5672; deBruijn et al., 1998, Cancer Research 58:724; Zitvogel et al., 1996, J. Exp. Med. 183:87; Okada et al., 1998, Int. J. Cancer 78:196; Ribas et al., 1997, Cancer Research 57:2865; Tuting et al., 1997, J. Mol. Med. 75:478]. Nevertheless, the most challenging obstacle for dendritic cell based immunotherapy has been the means by which to efficiently convey antigens to dendritic cells [Arthur et al., 1997, Cancer Gene Therapy 4:17; Van Tendeloo et al., 1998, Gene Therapy 5:700].
Adenovirus (Ad) has been employed as a vector to murine dendritic cells in generation of anti-tumoral immunity [Ribas et al., 1997, Cancer Research 57:2865; Brossart et al., 1997, J. Immunol. 158:3270; Kaplan et al., 1999, J. Immunol. 163:699; Gong et al., 1997, Gene Ther. 4:102; Song et al., 1997, J. Exp. Med. 186:1247]. The inefficiency of adenovirus mediated gene transfer, however, is likely to become problematic for large scale vaccinations.
Thus, the prior art is deficient in methods for transducing dendritic cells and B-cells for immunomodulatory purposes. Further, the prior art is deficient in effective methods of enhancing efficacy of dendritic cell-based vaccination. The present invention fulfills this long-standing need and desire in the art.